Respect OSVERSION in the pkg-install script. This allows package building
tinderboxes to do the righ thing reagrding Perl in a chroot/jail environment
regardless of the underlying host OS version.
Approved by: perl (tobez)

On recent 5-CURRENT, there is no Perl wrapper. It is therefore possible
that /usr/bin/perl5 doesn't exist, which violates some of use.perl's
assumptions. Take care of this case. [1]
Also in the case of a recent 5-CURRENT, automatically perform
"use.perl port" during package/port installation. This helps the
installation of sysinstall's new "Perl distribution", in that
sysinstall doesn't need to do this explicitly as Yet Another Special
Case. [2]
PORTREVISION bump after all this good stuff.
Requested by: bmah [1], jhb [2]
Submitted by: tobez (port MAINTAINER)
Approved by: portmgr (kris)